Signal processing circuit, signal processing method, and playback apparatus

1. A signal processing circuit configured so as to compose a feedback control loop that includes a loop filter and that detects the difference between a target value and a control value to control the difference so that the difference has a predetermined value, a closed loop formed in the feedback control loop being expressed by the delay of the entire closed loop serving as the feedback control loop, the loop filter, and simple integration of a final stage, the signal processing circuit comprising: moving average calculating means for calculating a moving average of outputs from the loop filter; multiplying means for multiplying a value calculated in the loop filter by a certain gain; and integrating means provided upstream of the loop filter so that a calculation result by the moving average calculating means and a calculation result by the multiplication means are concurrently fed back to an input into the loop filter.

2. The signal processing circuit according to claim 1 , wherein a control system for a secondary delay unit in which the loop filter includes a proportion filter and an integration filter is formed in the signal processing circuit, and wherein the multiplication means multiplies an integration term of the loop filter by the certain gain.

3. The signal processing circuit according to claim 2 , wherein the moving average calculating means calculates the moving average of a number of the outputs from the loop filter, the number of the outputs being given by subtracting one from the amount of delay in the entire closed loop, wherein the multiplication means multiplies the integration term of the loop filter by the amount of delay in the entire closed loop corresponding to the certain gain, and wherein the integrating means performs an addition and a subtraction so that the calculation result by the moving average calculating means is negatively fed back to the input into the loop filter and the calculation result by the multiplication means is positively fed back to the input into the loop filter.

4. The signal processing circuit according to claim 3 , wherein the signal processing circuit is a phase locked loop circuit that controls the phase and the frequency of an input signal.

5. A signal processing method wherein, when a closed loop formed in a feedback control loop that includes a loop filter and that detects the difference between a target value and a control value to control the difference so that the difference has a predetermined value is expressed by the delay of the entire closed loop serving as the feedback control loop, the loop filter, and simple integration of a final stage, a moving average of outputs from the loop filter and a value resulting from multiplication of a value calculated in the loop filter by a certain gain are concurrently fed back to an input into the loop filter.

6. A playback apparatus at least playing back data recorded on a recording medium, the playback apparatus comprising: readout means for reading out a signal recorded on the recording medium; and a phase locked loop circuit configured so as to serve as a control system for a secondary delay unit that includes a loop filter including a proportion filter and an integration filter, the phase locked loop circuit controlling the phase and frequency of the signal read out by the readout means, wherein the phase locked loop circuit is configured so that a closed loop formed in a feedback control loop is expressed by the delay of the entire closed loop serving as the feedback control loop, the loop filter, and simple integration of a final stage, and wherein the phase locked loop circuit includes moving average calculating means for calculating a moving average of outputs from the loop filter; multiplying means for multiplying an integration term of the loop filter by a certain gain; and integrating means provided upstream of the loop filter so that a calculation result by the moving average calculating means and a calculation result by the multiplication means are concurrently fed back to an input into the loop filter.

7. The playback apparatus according to claim 6 , wherein the moving average calculating means calculates the moving average of a number of the outputs from the loop filter, the number of the outputs being given by subtracting one from the amount of delay in the entire closed loop, wherein the multiplication means multiplies the integration term of the loop filter by the amount of delay in the entire closed loop corresponding to the certain gain, and wherein the integrating means performs an addition and a subtraction so that the calculation result by the moving average calculating means is negatively fed back to the input into the loop filter and the calculation result by the multiplication means is positively fed back to the input into the loop filter.

8. A signal processing circuit configured so as to compose a feedback control loop that includes a loop filter and that detects the difference between a target value and a control value to control the difference so that the difference has a predetermined value, a closed loop formed in the feedback control loop being expressed by the delay of the entire closed loop serving as the feedback control loop, the loop filter, and simple integration of a final stage, the signal processing circuit comprising: a moving average calculating unit configured to calculate a moving average of outputs from the loop filter; a multiplying unit configured to multiply a value calculated in the loop filter by a certain gain; and an integrating unit provided upstream of the loop filter so that a calculation result by the moving average calculating unit and a calculation result by the multiplication unit are concurrently fed back to an input into the loop filter.

9. A playback apparatus at least playing back data recorded on a recording medium, the playback apparatus comprising: a readout unit configured to read out a signal recorded on the recording medium; and a phase locked loop circuit configured so as to serve as a control system for a secondary delay unit that includes a loop filter including a proportion filter and an integration filter, the phase locked loop circuit controlling the phase and frequency of the signal read out by the readout unit, wherein the phase locked loop circuit is configured so that a closed loop formed in a feedback control loop is expressed by the delay of the entire closed loop serving as the feedback control loop, the loop filter, and simple integration of a final stage, and wherein the phase locked loop circuit includes a moving average calculating unit configured to calculate a moving average of outputs from the loop filter; a multiplying unit configured to multiply an integration term of the loop filter by a certain gain; and an integrating unit provided upstream of the loop filter so that a calculation result by the moving average calculating unit and a calculation result by the multiplication unit are concurrently fed back to an input into the loop filter.